The pipe connection between the basic unit and the additional module is via self-locking Schrader valves. The experimental set-up is arranged on a clearly laid out board, which is mounted on the basic unit. Individual components of the system, in this case the compressor, fan and solenoid valves are actuated using the software included with the basic unit.  The refrigerating capacity is generated by an evaporator. A fan transports the air to be cooled through a ventilation duct. The represents a model of a simple air conditioning unit for room cooling. Solenoid valves allow to operate the unit with a capillary tube or an expansion valve as expansion element. The airflow rate is determined indirectly by measuring the static and dynamic pressure. Temperature sensors record the temperature before and after the evaporator.